Azlactone chain transfer agents for radical polymerization

ABSTRACT

Chain transfer agents for controlled radical polymerizations (RAFT) are described. The chain transfer agents have an azlactone or ring-opened azlactone moiety to provide telechelic (co)polymers.

[0001] This application is a divisional of U.S. Ser. No. 10/429,487,filed May 5, 2003, now allowed, the disclosure of which is hereinincorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention provides initiators for reversibleaddition-fragmentation chain transfer (RAFT) polymerization processesand telechelic polymers made thereby.

BACKGROUND

[0003] In conventional radical polymerization processes, thepolymerization terminates when reactive intermediates are destroyed orrendered inactive; radical generation is essentially irreversible. It isdifficult to control the molecular weight and the polydispersity(molecular weight distribution) of polymers produced by conventionalradical polymerization, and difficult to achieve a highly uniform andwell-defined product. It is also often difficult to control radicalpolymerization processes with the degree of certainty necessary inspecialized applications, such as in the preparation of end functionalpolymers, block copolymers, star (co)polymers, and other noveltopologies.

[0004] In a controlled radical polymerization process radicals aregenerated reversibly, and irreversible chain transfer and chaintermination are absent. There are four major controlled radicalpolymerization methodologies: atom transfer radical polymerization(ATRP), reversible addition-fragmentation chain transfer (RAFT),nitroxide-mediated polymerization (NMP) and iniferters, each methodhaving advantages and disadvantages.

[0005] RAFT processes are among the most versatile controlled radicalpolymerization techniques, as reported by M. Freemantle, Chemical andEngineering News, Sep. 9, 2002, pp. 36-40. In a RAFT process apropagating polymer radical (P_(m).) adds to a chain transfer agent(P_(n)—X) to generate a new radical intermediate (P_(m)-X.—P_(n)). Thisintermediate radical fragments either to a new propagating radical(P_(n).) and a new dormant species (P_(m)—X), or back to (P_(m).) and(P_(n)—X). The RAFT chain transfer agent establishes a dynamicaddition-fragmentation equilibrium by transferring activity between thepropagating radicals and the dormant species. The polymerization may bereactivated by addition of more thermal—or photoinitiator and monomer.

[0006] There is a need for a radical polymerization process whichprovides (co)polymers having a predictable molecular weight and a narrowmolecular weight distribution (low “polydispersity”). A further need isstrongly felt for a radical polymerization process which is sufficientlyflexible to provide a wide variety of products, but which can becontrolled to the degree necessary to provide highly uniform productswith a controlled structure (i.e., controllable topology, composition,etc.). There is further need for a controlled radical polymerizationprocess which provides telechelic (co)polymers capable of entering intofurther polymerization or functionalization through reactive end-groups,particularly electrophilic end groups.

SUMMARY OF THE INVENTION

[0007] The present invention provides chain transfer agents (RAFTagents) for controlled radical polymerization processes that comprisecompounds of the formula:

[0008] wherein

[0009] R¹ and R² are each independently selected from H, an alkyl group,a nitrile group, a cycloalkyl group, a heterocyclic group, an arenylgroup and an aryl group, or R¹ and R² taken together with the carbon towhich they are attached form a carbocyclic ring;

[0010] R³ and R⁴ are each independently selected from an alkyl group, acycloalkyl group, an aryl group, an arenyl group, or R³ and R⁴ takentogether with the carbon to which they are attached form a carbocyclicring;

[0011] Y—S is a xanthate group of the formula R⁵—O—C(S)—S—, athioxanthate group (trithiocarbonate) of the formula R⁵—S—C(S)—S—, or adithioester group of the formula R⁵—C(S)—S—, wherein

[0012] R⁵ is selected from an alkyl group, a cycloalkyl group, an arylgroup, an arenyl group or a heterocyclic group, R⁵ is optionallysubstituted with phosphate, phosphonate, sulfonate, ester, halogen,nitrile, amide, and hydroxy groups; and R⁵ may optionally be substitutedwith one or more caternary heteroatoms, such as oxygen, nitrogen orsulfur;

[0013] Q is a linking group selected from a covalent bond, an arenylgroup, an aryl group, (—CH₂—)_(o), —CO—O—(CH₂)_(o)—,—CO—O—(CH₂CH₂O)_(o)—, —CO—NR⁸—(CH₂)_(o)—, —CO—S—(CH₂)_(o)—, where o is 1to 12, and R⁸ is H, an alkyl group, a cycloalkyl group, an arenyl group,a heterocyclic group, or an aryl group; and

[0014] n is 0 or 1.

[0015] The present invention also provides chain transfer agents thatcomprise the ring-opened reaction product of the chain transfer agentsof Formula I and a reactive compound, such as an aliphatic compound,having one or more nucleophilic groups. Such chain transfer agents havethe general formula:

[0016] wherein

[0017] R¹ and R² are each independently selected from H, a nitrilegroup, an alkyl group, a cycloalkyl group, an arenyl group, aheterocyclic group and an aryl group or R¹ and R² taken together withthe carbon to which they are attached form a carbocyclic ring; R³ and R⁴are each independently selected from an alkyl group, a cycloalkyl group,an aryl, an arenyl group, or R³ and R⁴ taken together with the carbon towhich they are attached form a carbocyclic ring;

[0018] Y—S is a xanthate group of the formula R⁵—O—C(S)—S—, athioxanthate group of the formula R⁵—S—C(S)—S—, or a dithioester groupof the formula R⁵—C(S)—S—, wherein R⁵ is selected from an alkyl group, acycloalkyl group, an aryl group, an arenyl group or a heterocyclicgroup, R⁵ is optionally substituted with phosphate, phosphonate,sulfonate, ester, halogen, nitrile, amide, and hydroxy groups; and R⁵may optionally be substituted with one or more caternary heteroatoms,such as oxygen, nitrogen or sulfur;

[0019] n is 0 or 1;

[0020] Z is O, S or NR⁸, wherein R⁸ is H, an alkyl group, a cycloalkylgroup, an arenyl group, a heterocyclic group or an aryl group;

[0021] R⁷ is an organic or inorganic moiety and has a valency of m, R⁷is the residue of a mono- or polyfunctional compound of the formulaR⁷(ZH)_(m);

[0022] Q is a linking group selected from a covalent bond, an arylgroup, an arenyl group, (—CH₂—)_(o), —CO—O—(CH₂)_(o)—,—CO—O—(CH₂CH₂O)_(o)—, —CO—NR⁸—(CH₂)_(o)—, —CO—S—(CH₂)_(o)—, where o is 1to 12, and R⁸ is H, an alkyl group, a cycloalkyl group, an aryl group,an arenyl group, a heterocyclic group or an aryl group;

[0023] m is an integer of at least 1, preferably at least 2.

[0024] The present invention also provides initiator compositions forcontrolled radical polymerization comprising the chain transfer agentsof Formulas I or II, and a thermal or photoinitiator.

[0025] The chain transfer agents of the present invention provide(co)polymers having a predictable molecular weight and a narrowmolecular weight distribution. Advantageously, the chain transfer agentsprovide novel multireactive addition polymers having first and secondterminal reactive groups that may be used for further functionalization.The present invention further provides a controlled radicalpolymerization process useful in the preparation ofterminal-functionalized (telechelic) (co)polymers, block copolymers,star (co)polymers, graft copolymers, and comb copolymers. The processprovides these (co)polymers with controlled topologies and compositions.

[0026] The control over molecular weight and functionality obtained inthis invention allows one to synthesize numerous materials with manynovel topologies for applications in coatings, surface modifications,elastomers, sealants, lubricants, pigments, personal care compositions,composites, inks, adhesives, dental resins, water treatment materials,hydrogels, imaging materials, telechelic materials and the like.

[0027] In another aspect, the invention provides a method forpolymerization of one or more olefinically unsaturated monomerscomprising addition polymerizing one or more olefinically unsaturatedmonomers using the initiator composition comprising the azlactone chaintransfer agents, or the ring-opened azlactone chain transfer agent and athermal or photoinitiator.

[0028] It is to be understood that the recitation of numerical ranges byendpoints includes all numbers and fractions subsumed within that range(e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0029] It is to be understood that all numbers and fractions thereof arepresumed to be modified by the term “about.”

[0030] It is to be understood that “a” as used herein includes both thesingular and plural.

[0031] The general definitions used herein have the following meaningswithin the scope of the present invention.

[0032] The term “alkyl” refers to straight or branched, cyclic oracyclic hydrocarbon radicals, such as methyl, ethyl, propyl, butyl,octyl, isopropyl, tert-butyl, sec-pentyl, cyclohexyl, and the like.Alkyl groups include, for example, 1 to 18 carbon atoms, preferably 1 to12 carbon atoms, or most preferably 1 to 6 carbon atoms.

[0033] The term “aryl” means the monovalent residue remaining afterremoval of one hydrogen atom from an aromatic compound that can consistof one two or three fused rings having 6 to 14 carbon atoms.

[0034] The term “arenyl” means the monovalent residue remaining afterremoval of a hydrogen atom from the alkyl portion of a hydrocarboncontaining both alkyl and aryl groups having 6 to 26 atoms.

[0035] The term “azlactone” means 2-oxazolin-5-one groups and2-oxazolin-6-one groups of Formula I, where n is 0 and 1, respectively.

[0036] The term “heterocyclic group” or “heterocycle” means themonovalent residue remaining after removal of one hydrogen atom from ancycloaliphatic or aromatic compound having one, two or three fused ringshaving 5 to 12 ring atoms and 1 to 3 heteroatoms selected from S, N, andnonperoxidic O. Useful heterocycles include azlactone, pyrrole, furan,thiophene, imidazole, pyrazole, thiazole, oxazole, pyridine, piperazine,piperidine, and hydrogenated and partially hydrogenated derivativesthereof.

[0037] The term “multifunctional” means the presence of more than one ofthe same functional reactive group;

[0038] The term “multireactive” means the presence of two or moredifferent functional reactive groups;

[0039] The term “polyfunctional” is inclusive of multireactive andmultifunctional.

[0040] The term “acid catalyst” or “acid catalyzed” means catalysis by aBrønsted- or Lewis-acid species;

[0041] The term “molecular weight” means number average molecular weight(M_(n)), unless otherwise specified.

[0042] The term (co)polymer refers to homo- and copolymers.

[0043] The term (meth)acrylate refers to both methacrylate and acrylate.

[0044] The term “telechelic” refers to (co)polymers having a functionalgroup on each terminus.

DETAILED DESCRIPTION

[0045] The present invention provides novel chain transfer agents ofFormula I and the corresponding ring-opened chain transfer agents ofFormula II for controlled radical polymerization processes.

[0046] wherein

[0047] R¹ and R² are each independently selected from H, an alkyl groupof 1 to 18 carbon atoms, a nitrile, a cycloalkyl group having 3 to 14carbon atoms, an aryl group having 6 to 14 ring atoms, an arenyl grouphaving 6 to 26 carbon atoms, a heterocyclic group having one, two orthree fused rings having 5 to 12 ring atoms and 1 to 3 heteroatomsselected from S, N, and nonperoxidic O; or R¹ and R² taken together withthe carbon to which they are attached form a carbocyclic ring containing4 to 12 ring atoms.

[0048] R³ and R⁴ are each independently selected from an alkyl grouphaving 1 to 18 carbon atoms, a cycloalkyl group having 3 to 14 carbonatoms, an aryl group having 6 to 14 ring atoms, an arenyl group having 6to 26 carbon atoms and 0 to 3 S, N, and nonperoxidic O heteroatoms, orR³ and R⁴ taken together with the carbon to which they are attached forma carbocyclic ring containing 4 to 12 ring atoms;

[0049] Y—S is a xanthate group of the formula R⁵—O—C(S)—S—, athioxanthate group of the formula R⁵—S—C(S)—S—, or a dithioester groupof the formula R⁵—C(S)—S—, wherein

[0050] R⁵ is selected from an alkyl group, a cycloalkyl group, an arylgroup, an arenyl group or a heterocyclic group, R⁵ is optionallysubstituted with phosphate, phosphonate, sulfonate, ester, halogen,nitrile, amide, and hydroxy groups; and R⁵ may optionally be substitutedwith one or more caternary heteroatoms, such as oxygen, nitrogen orsulfur. Note Y—S may be abbreviated as “S—Y”, or “SY”.

[0051] Z is O, NH, S or NR⁸, wherein R⁸ is a H, an alkyl group, acycloalkyl group, an aryl group an arenyl group or a heterocyclic group;

[0052] R⁷ is an organic or inorganic moiety and has a valency of m;

[0053] m is an integer of at least 1, preferably 1 to 8, most preferablyat least 2;

[0054] Q is a linking group selected from a covalent bond, an arylgroup, an arenyl group, (—CH₂—)_(o), —CO—O—(CH₂)_(o)—,—CO—O—(CH₂CH₂O)_(o)—, —CO—NR⁸—(CH₂)_(o)—-, —CO—S—(CH₂)_(o)—, where o is1 to 12, and R⁸ is H, an alkyl group, a cycloalkyl group, a heterocyclicgroup, or an aryl group;

[0055] and n is 0 or 1.

[0056] Chain transfer agents of Formula I may be prepared using thegeneralized sequence as shown:

[0057] In the above Scheme I, where X and X′ are halogen atoms or othersuitable leaving groups, an amino acid is first acylated, generally bydissolving the amino acid in aqueous base, followed by treatment withthe acyl halide compound under interfacial reaction conditions.Cyclization may be effected by treatment with acetic anhydride andpyridine, by treatment with carbodiimides, or preferably by treatmentwith ethyl chloroformate and a trialkylamine, which proceeds through amixed carboxylic-carbonic anhydride. The “Y—S” moiety is introduced bydisplacement of the X group, by a xanthic acid salt, a thioxanthic acidsalt or a dithiocarboxylate salt. Further details regarding thepreparation of azlactones may be found in “Polyaziactones”, Encyclopediaof Polymer Science and Engineering, vol. 11, 2^(nd) Ed., John Wiley andSons, pp. 558-571 (1988). With respect to the above reaction scheme, itwill be apparent that diacyl halide starting materials may be used toproduce dimeric or bis-azlactone chain transfer agents. Thesebis-azlactone chain transfer agents have the general structure:

[0058] wherein

[0059] Y—S is a xanthate group of the formula R⁵—O—C(S)—S—, athioxanthate of the formula R⁵—S—C(S)—S—, or a dithioester group of theformula R⁵—C(S)—S—, wherein R⁵ is selected from an alkyl group, acycloalkyl group, an aryl group, an arenyl group or a heterocyclicgroup, R⁵ is optionally substituted with phosphate, phosphonate,sulfonate, ester, halogen, nitrile, amide, and hydroxy groups; and R⁵may optionally be substituted with one or more caternary heteroatoms,such as oxygen, nitrogen or sulfur;

[0060] R¹ is selected from H, an alkyl group of 1 to 18 carbon atoms, acycloalkyl group having 3 to 14 carbon atoms, an aryl group having 6 to14 ring atoms, an arenyl group having 6 to 26 carbon atoms, aheterocyclic group having one, two or three fused rings having 5 to 12ring atoms and 1 to 3 heteroatoms selected from S, N, and nonperoxidicO;

[0061] R³ and R⁴ are each independently selected from an alkyl grouphaving 1 to 18 carbon atoms, a cycloalkyl group having 3 to 14 carbonatoms, an aryl group having 6 to 14 ring atoms, an arenyl group having 6to 26 carbon atoms and 0 to 3 S, N, and nonperoxidic O heteroatoms, orR³ and R⁴ taken together with the carbon to which they are attached forma carbocyclic ring containing 4 to 12 ring atoms;

[0062] R⁹ is a divalent alkylene group of 1 to 18 carbon atoms, acycloalkylene group having 3 to 14 carbon atoms, an aryl group having 6to 14 ring atoms, a heterocyclic group, or an arenyl group having 6 to26 carbon atoms,

[0063] Q is a linking group selected from a covalent bond, (—CH₂—)_(o),—CO—O—(CH₂)_(o)—, —CO—O—(CH₂CH₂O)_(o)—, —CO—NR⁸—(CH₂)_(o)—,—CO—S—(CH₂)_(o)—, where o is 1 to 12, and R⁸ is H, an alkyl group, acycloalkyl group, an arenyl group, a heterocyclic group or an arylgroup; and n is 0 or 1.

[0064] Useful azlactone chain transfer agents include the followingcompounds:

[0065] Ring-opened azlactone compounds of Formula II may be made bynucleophilic addition of a compound of the formula R⁷(ZH)_(m) to theazlactone carbonyl of Formula I as shown below. In the Scheme II, R⁷ isan inorganic or organic group having one or a plurality of nucleophilic-ZH groups, which are capable of reacting with the azlactone moiety ofFormula I. R⁷(ZH)_(m) may be water.

[0066] Alternatively, such ring opened compounds may be prepared bynucleophilic addition of a compound of the formula R⁷(ZH)_(m) to thehalogen-containing (“X”) azlactone, followed by displacement of the Xgroup with the “SY” group (by a xanthic acid salt, a thioxanthic acidsalt or dithiocarboxylic acid salt), as shown in Scheme III.

[0067] If organic, R⁷ may be a polymeric or non-polymeric organic groupthat has a valence of m and is the residue of a nucleophilicgroup-substituted compound, R⁷(ZH)_(m), in which Z is —O—, —S—, or —NRwherein R⁸ can be a H, an alkyl, a cycloalkyl or aryl, a heterocyclicgroup, an arenyl and m is at least one, preferably at least 2. Theorganic moiety R⁷ is preferably selected from mono- and polyvalenthydrocarbyl (i.e., aliphatic and aryl compounds having 1 to 30 carbonatoms and optionally zero to four heteroatoms of oxygen, nitrogen orsulfur), polyolefin, polyoxyalkylene, polyester, polyolefin,poly(meth)acrylate, or polysiloxane backbones. If inorganic, R⁷ maycomprise silica, alumina or glass having one or a plurality of -ZHgroups on the surface.

[0068] In one embodiment, R⁷ comprises a non-polymeric aliphatic,cycloaliphatic, aromatic or alkyl-substituted aromatic moiety havingfrom 1 to 30 carbon atoms. In another embodiment, R⁷ comprises apolyoxyalkylene, polyester, polyolefin, poly(meth)acrylate, polystyreneor polysiloxane polymer having pendent or terminal reactive -ZH groups.Useful polymers include, for example, hydroxyl, thiol or aminoterminated polyethylenes or polypropylenes, hydroxyl, thiol or aminoterminated poly(alkylene oxides) and poly(meth)acylates having pendantreactive functional groups, such as hydroxyethyl acrylate polymers andcopolymers.

[0069] Depending on the nature of the functional group(s) of R⁷(ZH)_(m),a catalyst may be added to effect the condensation reaction. Normally,primary amine groups do not require catalysts to achieve an effectiverate. Acid catalysts such as trifluoroacetic, ethanesulfonic, andtoluenesulfonic acids are effective with hydroxyl groups and secondaryamines. Basic catalysts such as DBU (1,8-diazabicyclo[5.4.0]undec-7-ene)and DBN are also effective.

[0070] With respect to the compound R⁷(ZH)_(m), m is at least one, butpreferably m is at least two. The multiple -ZH groups of thepolyfunctional compound may be the same or different. Multifunctionalcompounds may be reacted with the azlactone compound of Formula I toproduce polyfunctional chain transfer agents of Formula II, where m isat least two. Such polyfunctional chain transfer agents allow thepreparation of graft, branched, and star (co)polymers and other usefultopologies.

[0071] Useful alcohols of the formula R⁷(ZH)_(m) include aliphatic andaromatic monoalcohols and polyols. Useful monoalcohols include methanol,ethanol, octanol, decanol, and phenol. The polyols useful in the presentinvention include aliphatic or aromatic polyols having at least twohydroxyl groups. Examples of useful polyols include ethylene glycol,propylene glycol, butanediol, 1,3-pentane diol, 2,2-oxydiethanol,hexanediol, poly(pentyleneadipate glycol), poly(tetramethylene etherglycol), poly(ethylene glycol), poly(caprolactone diol),poly(1,2-butylene oxide glycol), trimethylol ethane, trimethylolpropane, trimethyol aminomethane, ethylene glycol, 2-butene-1,4-diol,pentaerythritol, dipentaerythritol, and tripentaerythritol. The term“polyol” also includes derivatives of the above-described polyols suchas the reaction product of the polyol with di- or poly-isocyanate, ordi- or poly-carboxylic acid, the molar ratio of polyol to —NCO, or —COOHbeing at least 1 to 1.

[0072] Useful amines of the formula R⁷(ZH)_(m) include aliphatic andaromatic monoamines and polyamines. Any primary or secondary amine maybe employed, although primary amines are preferred to secondary amines.Useful monoamines include, for example, methyl-, ethyl-, propyl-,hexyl-, octyl, dodecyl-, dimethyl-, methyl ethyl-, and aniline. The term“di-, or polyamine,” refers to organic compounds containing at least twonon-tertiary amine groups. Aliphatic, aromatic, cycloaliphatic, andoligomeric di- and polyamines all are considered useful in the practiceof the invention. Representative of the classes of useful di- orpolyamines are 4,4′-methylene dianiline,3,9-bis-(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, andpolyoxyethylenediamine. Many di- and polyamines, such as those justnamed, are available commercially, for example, those available fromHuntsman Chemical, Houston, Tex. The most preferred di- or polyaminesinclude aliphatic diamines or aliphatic di- or polyamines and morespecifically compounds with two primary amino groups, such as ethylenediamine, hexamethylene diamine, dodecanediamine, and the like.

[0073] Useful thiols of the formula R⁷(ZH)_(m) include aliphatic andaromatic monothiols and polythiols Useful alkyl thiols include methyl,ethyl and butyl thiol, as well as 2-mercaptoethanol,3-mercapto-1,2-propanediol, 4-mercaptobutanol, mercaptoundecanol,2-mercaptoethylamine, 2,3-dimercaptopropanol,3-mercaptopropyltrimethoxysilane, 2-chloroethanethiol,2-amino-3-mercaptopropionic acid, dodecyl mercaptan, thiophenol,2-mercaptoethyl ether, and pentaerythritol tetrathioglycolate. Usefulsoluble, high molecular weight thiols include polyethylene glycoldi(2-mercaptoacetate), LP-3™ resins supplied by Morton Thiokol Inc.(Trenton, N.J.), and Permapol P3™ resins supplied by Products Research &Chemical Corp. (Glendale, Calif.) and compounds such as the adduct of2-mercaptoethylamine and caprolactam.

[0074] The invention provides multifunctional chain transfer agents ofFormula II, whereby an azlactone chain transfer agent of Formula I isring-opened by a multireactive or multifunctional compound of theformula R⁷(ZH)_(m), where m is at least 2. Such multifunctional chaintransfer agents may be used to produce branched, star and graft(co)polymers and other topologies. It will also be apparent that such(co)polymers may also be prepared by first polymerizing a monomer usingthe chain transfer agent of Formula I, to produce polymers having anazlactone group at one terminal end, and then subsequently reacting thepolymers with a polyfunctional compound of the formula R⁷(ZH)_(m), wherem is at least 2.

[0075] In another embodiment, the multifunctional chain transfer agentsmay comprise a solid support having a plurality of chain transfer agentmoieties on the surface thereof. Such chain transferagent-functionalized supports have the general structure (correspondingto Formula II):

[0076] wherein Y—S, R¹, R², R³, Q, Z, n and m are as previouslydescribed for Formula II and SS is a solid support corresponding to R⁷.The solid support material includes functional groups to which chaintransfer agent molecules of Formula I can be covalently attached forbuilding large or small organic compounds. Useful functional groupsinclude hydroxyl, amino and thiol functional groups corresponding to-ZH.

[0077] The support material can be organic or inorganic. It can be inthe form of solids, gels, glasses, etc. It can be in the form of aplurality of particles (e.g., beads, pellets, or microspheres), fibers,a membrane (e.g., sheet or film), a disc, a ring, a tube, or a rod, forexample. Preferably, it is in the form of a plurality of particles or amembrane. It can be swellable or non-swellable and porous or nonporous.

[0078] The support material can be a polymeric material that can be usedin conventional solid phase synthesis. It is chosen such that it isgenerally insoluble in the solvents or other components used insynthetic reactions that occur during the course of solid phasesynthesis. The support material can be a soluble or insoluble polymerhaving a molecular weight of 10,000 up to infinity for crosslinkingpolymers.

[0079] Examples of useable pre-existing support materials are describedin G. B. Fields et al., Int. J. Peptide Protein Res., 35, 161 (1990) andG. B. Fields et al., in Synthetic Peptides. A User's Guide, G. A. Grant,Ed., pages 77-183, W.H. Freeman and Co., New York, N.Y. (1992). Thesupport material is in the form of an organic polymeric material, suchas polystyrenes, polyalkylenes, nylons, polysulfones, polyacrylates,polycarbonates, polyesters, polyimides, polyurethanes, etc. and havinghydroxyl, amino or thiol substituents on the surface. For pre-existingsupport materials, a preferred support material is polystyrene.

[0080] In the present polymerization, the amounts and relativeproportions of chain transfer agent and monomer are those effective toconduct radical polymerization. Accordingly, the amount of chaintransfer agent can be selected such that the chain transfer agentconcentration is from 10⁻⁵ M to 1 M, preferably 10⁻⁴ to 10⁻² M.Alternatively, the chain transfer agent can be present in a molar ratioof from 10⁻⁵:1 to 10⁻⁵:1, preferably from 10⁻⁵:1 to 2×10⁻³:1, relativeto monomer.

[0081] The initiator compositions of the present invention comprise thechain transfer agents of Formulas I or II and a thermal orphotoinitiator.

[0082] Useful thermal initiators include azo, peroxide, persulfate, andredox initiators.

[0083] Suitable azo initiators include2,2′-azobis(2,4-dimethylvaleronitrile) (VAZO™ 52);2,2′-azobis(isobutyronitrile) (VAZO™ 64);2,2′-azobis-2-methylbutyronitrile (VAZO™ 67); and(1,1′-azobis(1-cyclohexanecarbonitrile) (VAZO™ 88), all of which areavailable from DuPont Chemicals, and 2,2′-azobis(methyl isobutyrate)(V-601) and 2,2′-azobis(2-amidinopropane)dihydrochloride (V-50)available from Wako Chemicals. Also suitable is2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile), formerly availablefrom DuPont Chemicals as VAZO™ 33.

[0084] Suitable peroxide initiators include benzoyl peroxide, acetylperoxide, lauroyl peroxide, decanoyl peroxide, diacetylperoxydicarbonate, di(4-t-butylcyclohexyl) peroxydicarbonate (PERKADOX™16S, available from AKZO Chemicals), di(2-ethylhexyl) peroxydicarbonate,t-butyl peroxybenzoate, t-butyl peroxypivalate (LUPERSOL™ 1, availablefrom Atochem), t-butyl peroxy-2-ethylhexanoate (TRIGONOX™ 21-C50,available from Akzo Chemicals, Inc.), and dicumyl peroxide.

[0085] Suitable persulfate initiators include potassium persulfate,sodium persulfate, and ammonium persulfate.

[0086] Suitable redox (oxidation-reduction) initiators includecombinations of the above persulfate initiators with reducing agentssuch as sodium metabisulfite and sodium bisulfite; systems based onorganic peroxides and tertiary amines (for example, benzoyl peroxideplus dimethylaniline); and systems based on organic hydroperoxides andtransition metals, for example, cumene hydroperoxide plus cobaltnaphthenate.

[0087] Preferred thermal free-radical initiators are selected from thegroup consisting of azo compounds and peroxides, e.g., LUPERSOL™1 andPERKADOX 16, and mixtures thereof.

[0088] Useful photoinitiators are those capable of being activated by UVradiation, e.g., at wavelengths from about 250 nm to about 450 nm, morepreferably at about 351 nm. Useful photoinitiators include e.g., benzoinethers such as benzoin methyl ether and benzoin isopropyl ether,substituted benzoin ethers, arylphospine oxide, substitutedacetophenones such as 2,2-dimethoxy-2-phenylacetophenone, andsubstituted alpha-ketols (alpha-hydroxyketones). Examples ofcommercially available photoinitiators include Irgacure™ 819 andDarocur™ 1173 (both available form Ciba-Geigy Corp., Hawthorne, N.Y.),Lucern TPO™ (available from BASF, Parsippany, N.J.) and Irgacure™ 651,(2,2-dimethoxy-1,2-diphenyl-1-ethanone), available from Ciba-Geigycorporation.

[0089] The thermal or photoinitiator is used in an amount effective tofacilitate fragmentation of the azlactone chain transfer agent and theamount will vary depending upon, e.g., the type of initiator, and themonomer(s), and the desired molecular weight of the resulting(co)polymer. The initiators can be used in molar ratios from about0.001:1 to 1:1, preferably 0.001:1 to 0.1:1 relative to the chaintransfer agent. If desired, the initiator may be added in bulk, may beadded intermittently, or may be continuously added. When preparing blockcopolymers, it is advantageous to add an initial charge of initiatorwith the chain transfer agent and monomer(s), polymerize to essentialcompletion (i.e. depletion of the first monomer charge), then addadditional initiator with the charge of a second monomer(s).

[0090] Examples of olefinically unsaturated monomers that may bepolymerized include (meth)acrylic acid; (meth)acrylates such as ethyl(meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isooctyl(meth)acrylate and other alkyl (meth)acrylates; also functionalized(meth)acrylates including glycidyl (meth)acrylate, poly(ethyleneoxide)(meth)acrylate, trimethoxysilyl propyl (meth)acrylate, allyl(meth)acrylate, hydroxyethyl (meth)acrylate, hydroxypropyl(meth)acrylate, mono- and dialkyl aminoalkyl (meth)acrylates;mercaptoalkyl (meth)acrylates, fluoroalkyl (meth)acrylates;(meth)acrylic acid, fumaric acid (and esters), itaconic acid (andesters), maleic anhydride; styrenics such as α-methyl styrene,functionailized styenes, t-butylstyrene, acetoxystyrene; vinyl halidessuch as vinyl chloride and vinyl fluoride; (meth)acrylonitrile,vinylidene halides; vinyl esters of carboxylic acids such as vinylacetate and vinyl propionate; amides of vinyl amine such as vinylformamide or vinyl acetamide; monomers containing a secondary, tertiaryor quaternary amino group such as vinyl pyridine, butadienes;unsaturated alkylsulphonic acids or derivatives thereof;2-vinyl-4,4-dimethylazlactone, N-vinyl pyrrolidinone. Mixtures of suchmonomers may be used.

[0091] Monomers having pendent, nucleophilic functional groups such ashydroxy-, amino- or thiol-functional groups are particularly useful forproviding so-called AB_(n) polymers. Such pendent nucleophilicfunctional groups may react with the azlactone terminal group to providenovel architectures. Such pendent nucleophilic functional groups may beprotected during the polymerization, and deprotected post-polymerizationfor providing novel polymer architecture. In light initiatedpolymerizations, such functional groups may not required protection forsubsequent thermal reaction.

[0092] Some of the above monomers, such as styrene, are autocatalytic;they will generate free radicals at elevated temperatures. Such monomersmay be polymerized with the chain transfer agents without the additionof a thermal or photoinitiators.

[0093] The present polymerization may be conducted in bulk, or in asolvent. Solvents, preferably organic, can be used to assist in thedissolution of the chain transfer agent in the polymerizable monomers,and as a processing aid. Preferably, such solvents are not reactive withthe azlactone group. Suitable solvents include ethers such as diethylether, ethyl propyl ether, dipropyl ether, methyl t-butyl ether,di-t-butyl ether, glyme (dimethoxyethane), diglyme, diethylene glycoldimethyl ether; cyclic ethers such as tetrahydrofuran and dioxane;alkanes; cycloalkanes; aromatic hydrocarbon solvents such as benzene,toluene, o-xylene, m-xylene, p-xylene; halogenated hydrocarbon solvents;acetonitrile; lactones such as butyrolactone, and valerolactones;ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone,cyclopentanone, and cyclohexanone; sulfones such as tetramethylenesulfone, 3-methylsulfolane, 2,4-dimethylsulfolane, butadiene sulfone,methyl sulfone, ethyl sulfone, propyl sulfone, butyl sulfone, methylvinyl sulfone, 2-(methylsulfonyl)ethanol, and 2,2′-sulfonyldiethanol;sulfoxides such as dimethyl sulfoxide; cyclic carbonates such aspropylene carbonate, ethylene carbonate and vinylene carbonate;carboxylic acid esters such as ethyl acetate, Methyl Cellosolve™ andmethyl formate; and other solvents such as methylene chloride,nitromethane, acetonitrile, glycol sulfite and mixtures of suchsolvents, and supercritical solvents (such as CO₂). The presentpolymerization may be conducted in accordance with known polymerizationprocesses.

[0094] Polymerizing may be conducted at a temperature of from −78 to200° C.

[0095] Autocatalytic monomers may be polymerized at temperatures abovetheir respective autoinitiation temperatures. Styrene, for example, maybe polymerized at temperatures above about 110° C. in the absence ofinitiator. Polymerization with thermal initiators may be preferablyconducted from 0 to 160° C. and most preferably from 0 to 80° C. Thereaction should be conducted for a length of time sufficient to convertat least 1% of the monomer to polymer. Typically, the reaction time willbe from several minutes to 5 days, preferably from 30 minutes to 3 days,and most preferably from 1 to 24 hours.

[0096] Polymerizing may be conducted at a pressure of from 0.1 to 100atmospheres, preferably from 1 to 50 atmospheres and most preferably atambient pressure (although the pressure may not be measurable directlyif conducted in a sealed vessel). An inert gas such as nitrogen or argonmay be used.

[0097] While not wishing to be bound by theory, it is believed that thepolymerization occurs by the following sequence:

[0098] Initiation

I.+monomer

M_(n)·

[0099] Chain transfer

M_(n).+YS-Az

[YS-M_(n)-Az].

YS-M_(n)+Az·

[0100] Reinitiation

Az.+monomer

Az-M_(m)·

[0101] Chain equilibration

Az-M_(m).+YS-M_(n)

[Az-M_(m)-YS-M_(n)].

Az-M_(m)-SY+M_(n).

[0102] In the above scheme, a propagating polymer radical M_(n). adds tothe chain transfer agent, YS-Az, to generate a new radical,[YS-M_(n)-Az].. This intermediate radical either fragements into a newpropagating radical Az. and a new dormant species YS-M_(n), or back toM_(n). and YS-Az. The RAFT chain transfer agent establishes a dynamicaddition-fragmentation equilibrium by transferring activity between thepropagating radicals and the dormant species.

[0103] The (co)polymers obtained by the method of the invention may bedescribed as telechelic (co)polymers comprising polymerized units of oneor more free radically (co)polymerizable monomers (as previouslydescribed), a first azlactone terminal group derived from the chaintransfer agent of Formula I and a second terminal group selected from axanthate group, a thioxanthate group or a dithioester group (derivedfrom “YS” group). Alternatively, when using the chain transfer agents ofFormula II, the first terminal group “Az” will comprise the ring-openedresidue of the azlactone group of the Formula III:

[0104] where R¹, R², R³, R⁴, R⁷, Z, Q, m and n are as previouslydefined.

[0105] Such (co)polymers have the general formulaAz-(M¹)_(x)(M²)_(x)(M³)_(x) . . . (M^(Ω))_(x)—S—Y, wherein “SY” is axanthate group, a thioxanthate group or a dithioester group as definedin Formulas I and II;

[0106] M¹ to M^(Ω) are each polymerized monomer units derived from aradically (co)polymerizable monomer unit having an average degree ofpolymerization x, each x is independent, and Az is an azlactone group ora ring-opened azlactone group of Formula III. Further, the polymerproduct retains the functional group “YS” at one terminal end of thepolymer necessary to initiate a further polymerization (orfunctionalization). The polymer product further comprises either theazlactone moiety or the ring-opened azlactone moiety of the chaintransfer agent at the other terminal end, which may be further reactedor functionalized as desired. Because the two terminal moieties havedifferent functionality and reactivity, each terminus may beindependently functionalized.

[0107] The terminal “Y—S” group may be functionalized independently fromthe terminal “Az” group. For example, functionalization of the aziactonefollowed by mild hydrolysis of the “YS” groups yields thiols, whichreadily oxidize to form a dimeric polymer linked by a disulfide group.Reduction of the disulfide linkage to yields a thiol group, which thenmay be further functionalized. Further, it has been discovered thathydroxy-, amino- and thio-compounds add preferentially to the azlactoneterminal group rather than the “YS” terminal group, allowing independentfunctionalization. The first and second terminal groups of the(co)polymers may be used to functional the surface of a solid support,by judicicious choice of a co-reactive functional group on the surfaceof the support.

[0108] The present invention encompasses a novel process for preparingrandom, block, multi-block, star, gradient, random hyperbranched anddendritic copolymers, as well as graft or “comb” copolymers. Each ofthese different types of copolymers will be described hereunder.

[0109] Since RAFT polymerization is a “living” or “controlled”polymerization, it can be initiated and terminated as desired. Thus, inone embodiment, once the first monomer is consumed in the initialpolymerizing step, a second monomer can then be added to form a secondblock on the growing polymer chain in a second polymerizing step.Additional polymerizations with the same or different monomer(s) can beperformed to prepare multi-block copolymers.

[0110] Because RAFT polymerization is a radical polymerization, blockscan be prepared in essentially any order. One is not necessarily limitedto preparing block copolymers where the sequential polymerizing stepsmust flow from the least stabilized polymer intermediate to the moststabilized polymer intermediate, such as is necessary in ionicpolymerization. Thus, one can prepare a multi-block copolymer in which apolyacrylonitrile or a poly(meth)acrylate block is prepared first, thena styrene or butadiene block is attached thereto, etc.

[0111] Furthermore, a linking group is not necessary to join thedifferent blocks of the present block copolymer. One can simply addsuccessive monomers to form successive blocks. Further, it is alsopossible (and in some cases advantageous) to first isolate a (co)polymerproduced by the present chain transfer agent polymerization process,then react the polymer with an additional monomer. In such a case, theproduct polymer having a terminal “Y—S” group acts as the new chaintransfer agent for the further polymerization of the additional monomer.

[0112] Since the novel chain transfer agents provide a reactive group“Az” at a terminal end of the polymer, linking groups may be used tojoin two polymer blocks. For example, in one embodiment, a polymerprepared in accord with the present invention, and having an azlactonegroup at one terminus, may be reacted with a second polymer block havinga nucleophilic terminal group.

[0113] Statistical copolymers may be produced using the chain transferagents of the present invention. Such copolymers may use two or moremonomers in a range of about 0-100% by weight of each of the monomersused. The product copolymer will be a function of the molar amounts ofthe monomers used and the relative reactivity of the monomers.

[0114] The present invention also provides graft or “comb” copolymers.Here, a first (co)polymer having pendent nucleophilic functional groups,such as hydroxy-, amino- or thio-groups, etc. is provided. An example ofuseful (co)polymers include hydroxyethyl acrylate (co)polymers. Next,the reactive functional groups of the first (co)polymer is reacted withthe azlactone chain transfer agents of Formula I to provide a(co)polymer having pendent, ring-opened chain transfer agent moieties,the reaction product having the structure of Formula II, where R⁷ is theresidue of the first (co)polymer. This product (co)polymer may then beused as an chain transfer agent to polymerize the previously-describedmonomers to produce a comb (co)polymer. Alternatively, the first(co)polymer may be reacted with a telechelic (co)polymer of theinvention, whereby the reactive “Az” terminal group reacts with thependent reactive group of the first (co)polymer.

[0115] Gradient or tapered copolymers can be produced using RAFTpolymerization by controlling the proportion of two or more monomersbeing added. For example, one can prepare a first block or an oligomerof a first monomer, then a mixture of the first monomer and a seconddistinct monomer can be added in proportions of from, for example, 1:1to 9:1 of first monomer to second monomer. After conversion of allmonomer(s) is complete, sequential additions of first monomer-secondmonomers mixtures can provide subsequent “blocks” in which theproportions of first monomer to second monomer vary. Thus, the inventionprovides copolymers obtained from two or more radically(co)polymerizable monomers wherein the copolymer has a composition thatvaries along the length of the polymer chain from azlactone terminus toopposite terminus based on the relative reactivity ratios of themonomers and instantaneous concentrations of the monomers duringpolymerization.

EXAMPLES

[0116] All reagents and solvents, unless otherwise noted, were purchasedfrom Aldrich (Milwaukee, Wis.) and were used in their deliveredcondition. Polymerizable reagents were stripped of inhibitors prior touse by passing them through an alumina column (also supplied byAldrich). Solvents were purchased from EM Science located in Gibbstown,N.J.

[0117] Compounds described in the Examples were found to have ¹H NMR andIR spectra that were consistent with the assigned structure.

Preparative Example 1

[0118] Preparation of 2-(2-Chloro-acetylamino)-2-methyl propionic acid.

[0119] To a stirring mixture of 2-aminoisobutyric acid (165.8 g; 1.61mol), sodium hydroxide (64.4 g; 1.61 mol) and 800 mL water, cooled to 5°C., was added chloroacetyl chloride (200 g; 1.77 mol) and then asolution of sodium hydroxide (70.8 g; 1.77 mol) in 143 mL water. Thetemperature was maintained between 5 to 10° C. during the additions. Thereaction mixture was then allowed to warm to room temperature and thesolution was acidified with 165 mL of concentrated aqueous HCl. Theprecipitated solid was filtered and dried under vacuum to afford 180.4 g(62%) of product.

Preparative Example 2

[0120] Preparation of 2-Chloromethyl-4,4-dimethyl-4H-oxazol-5-one.

[0121] To a stirring mixture of 2-(2-chloro-acetylamino)-2-methylpropionic acid (18.0 g; 0.10 mol), triethylamine (11.1 g; 0.11 mol) and100 mL acetone, cooled with an ice bath, was added ethyl chloroformate(10.5 mL; 0.11 mol) over a period of 10 minutes. The reaction mixturewas then allowed to warm to room temperature and was stirred for 2hours. The mixture was then filtered, and the filtrate was concentratedunder vacuum. Hexane (200 mL) was added to the residue, and the mixturewas filtered. After removal of the solvent under vacuum, the filtrateresidue was distilled under reduced pressure (59-60° C.; 7 mmHg) to give13.2 g (82%) of a colorless oil.

Preparative Example 3

[0122] Preparation of 2-(2-Bromo-propionylamino)-2-methyl-propionicacid.

[0123] To a stirring mixture of 2-aminoisobutyric acid (52.08 g; 0.51mol), sodium hydroxide (20.20 g; 0.51 mol), 200 mL water and 50 mLchloroform cooled to −12° C., was added a solution of 2-bromopropionylbromide (100 g; 0.463 mol) in 150 mL chloroform. The temperature wasmaintained between −15 to −12° C. during the addition. The reactionmixture was then allowed to warm to room temperature and stirred for 17hours. The precipitated solid was filtered, mixed with 700 mL hottoluene, then cooled to room temperature. The solid was filtered anddried under vacuum to afford 77.6 g (70%) of product.

Preparative Example 4

[0124] Preparation of 2-(1-Bromo-ethyl)-4,4-dimethyl-4H-oxazol-5-one.

[0125] To a stirring mixture of2-(2-bromo-propionylamino)-2-methyl-propionic acid (50.0 g; 0.21 mol),triethylamine (23.37 g; 0.23 mol) and 150 mL acetone, cooled with an icebath, was added a solution of ethyl chloroformate (25.07 g; 0.23 mol) in40 mL acetone over a period of 10 minutes. The reaction mixture was thenallowed to warm to room temperature and was stirred for 2 hours. Themixture was then filtered, and the solid was washed with 150 mL ether.The combined filtrate was concentrated under vacuum. Ether (100 mL) wasadded to the residue, and the mixture was filtered. After removal of thesolvent under vacuum, the filtrate residue was distilled under reducedpressure (63-64° C.; 1 mmHg) to give 34.73 g (75%) of a colorless oil.

Preparative Example 5

[0126] Preparation ofN-[2-(Bis-{2-[2-(2-chloro-acetylamino)-2-methyl-propionylamino]-ethyl}-amino)-ethyl]-2-(2-chloro-acetylamino)-2-methyl-propionamide.

[0127] To a solution of 2-chloromethyl-4,4-dimethyl-4H-oxazol-5-one(2.00 g; 12.4 mmol) in 35 mL acetone was added dropwise a solution oftris(2-aminoethyl)amine in 2 mL acetone. The mixture was stirred for 30minutes, then concentrated under vacuum to give 2.30 g (89%) of a yellowsolid.

Example 1

[0128] Preparation of dithiocarbonic acidS-(4,4-dimethyl-5-oxo-4,5-dihydro-oxazol-2-ylmethyl)ester O-ethyl ester(AzTC).

[0129] To a solution of 2-chloromethyl-4,4-dimethyl-4H-oxazol-5-one(15.67 g; 97 mmol) and 125 mL acetonitrile was added O-ethyl xanthicacid potassium salt (15.55 g; 97 mmol). The mixture was stirred under anitrogen atmosphere at room temperature for 16 hours. The reactionmixture was filtered and the solid was washed with 50 mL acetonitrile.The combined filtrate was concentrated under reduced pressure to afford21.79 g (91%) of AzTC as a yellow crystalline solid.

Example 2

[0130] Preparation of dithiocarbonic acidS-[1-(4,4-dimethyl-5-oxo-4,5-dihydro-oxazol-2-yl)-ethyl]ester O-ethylester.

[0131] To a solution of 2-(1-bromo-ethyl)-4,4-dimethyl-4H-oxazol-5-one(3.00 g; 13.6 mmol) and 50 mL acetonitrile was added O-ethyl xanthicacid potassium salt (2.18 g; 13.6 mmol). The mixture was stirred under anitrogen atmosphere at room temperature for 5 hours. The reactionmixture was filtered and the solid was washed with 10 mL acetontrile 10mL. The combined filtrate was concentrated under reduced pressure toafford 2.89 g (81%) of dithiocarbonic acidS-[1-(4,4-dimethyl-5-oxo-4,5-dihydro-oxazol-2-yl)-ethyl]ester O-ethylester as a yellow oil.

Example 3

[0132] Preparation of Dithiocarbonic acidS-({1-[2-(bis-{2-[2-(2-ethoxythiocarbonylsulfanyl-acetylamino)-2-methyl-propionylamino]-ethyl}-amino)-ethylcarbamoyl]-1-methyl-ethylcarbamoyl}-methyl)esterO-ethyl ester (tris(ring-opened AzTC)amine).

[0133] To a mixture ofN-[2-(bis-{2-[2-(2-chloro-acetylamino)-2-methyl-propionylamino]-ethyl}-amino)-ethyl]-2-(2-chloro-acetylamino)-2-methyl-propionamide(1.00 g; 1.54 mmol) and 20 mL acetonitrile was added O-ethyl xanthicacid potassium salt (0.761 g; 4.75 mmol). After stirring the mixture atroom temperature for 5 hr, additional O-ethyl xanthic acid potassiumsalt (0.370 g; 2.31 mmol) was added. After stirring for an additional 5hours at room temperature, the mixture was filtered. The filtrate wasconcentrated under reduced pressure to to afford 1.20 g (87%) of thetris(ring-opened AzTC)amine as a red solid.

Example 4

[0134] Synthesis of Az-P(EHA)-TC via the Controlled Polymerization of2-Ethylhexyl Acrylate with AzTC.

[0135] A solution of 0.305 g (1.23 mmol) of the product of Example 1(AzTC), 8.59 g 2-ethylhexyl acrylate, 17 mg 2,2′-azobisisobutyronitrileand 9.01 g ethyl acetate was placed in a screw cap vial. The solutionwas sparged with nitrogen for 20 minutes, and the vial was sealed. Thevial was heated in an oil bath at 70° C. for 4.75 hours. A small aliquotof the reaction mixture was weighed and was then concentrated to drynessby heating in an oven at 50° C. for 16 hours. The ratio of the mass ofeach dried sample to the mass of the aliquot of reaction mixture wasused to calculate the percent conversion of the monomer. The conversionwas 97%. Analysis of the polymer by gel permeation chromatography intetrahydrofuran showed M_(n)=5720 and polydispersity=1.88.

Example 5

[0136] Synthesis of Az-PSt-TC via the Controlled Polymerization ofStyrene with Thiocarbonic acidS-[1-(4,4-dimethyl-5-oxo-4,5-dihydro-oxazol-2-yl)-ethyl]ester O-ethylester.

[0137] A solution 0.327 g (1.25 mmol) of the product of Example 2(dithiocarbonic acidS-[1-(4,4-dimethyl-5-oxo-4,5-dihydro-oxazol-2-yl)-ethyl]ester O-ethylester), 5.00 g styrene and 0.40 g of a 2 wt % solution of2,2′-azobisisobutyronitrile in ethyl acetate was placed in a screw capvial. The solution was sparged with nitrogen for 25 minutes, and thevial was sealed. The vial was placed in an oven at 70° C. for 24 hours.The polymer was then precipitated into 50 mL petroleum ether. The liquidwas decanted, and an additional 60 mL petroleum ether was added. Themixture was shaken for 24 hours, then the solvent was decanted. Therecovered polymer was dried under vacuum (2.50 g). Analysis of thepolymer by gel permeation chromatography in tetrahydrofuran showedM_(n)=2820 and polydispersity=1.84.

Example 6

[0138] Synthesis of Synthesis of Az-P(IBA)-TC via the ControlledPolymerization of 2-Ethylhexyl Acrylate with dithiocarbonic acidS-[1-(4,4-dimethyl-5-oxo-4,5-dihydro-oxazol-2-yl)-ethyl]ester O-ethylester.

[0139] A solution of 0.183 g (0.70 mmol) of the product of Example 2(dithiocarbonic acidS-[1-(4,4-dimethyl-5-oxo-4,5-dihydro-oxazol-2-yl)-ethyl]ester O-ethylester), 5.00 g isobornyl acrylate, 5.70 g ethyl acetate and 0.46 g of a2 wt % solution of 2,2′-azobisisobutyronitrile in ethyl acetate wasplaced in a screw cap vial. The solution was sparged with nitrogen for20 minutes, then the vial was sealed. The vial was placed in an oven at70° C. for 7 hours. The polymer was then precipitated into methanol andfiltered. The recovered polymer was dried under vacuum. Analysis of thepolymer by gel permeation chromatography in tetrahydrofuran showedM_(n)=3630 and polydispersity=1.83.

Example 7

[0140] Synthesis of a Poly(Isobornyl Acrylate) Star Polymer withTris(ring-opened AzTC)amine.

[0141] A mixture of 0.105 g (0.12 mmol) of the product from Example 3(tris(ring-opened AzTC)amine), 1.20 g isobornyl acrylate, 1.50 gtetrahydrofuran, and 0.369 g of a 2 wt % solution of2,2′-azobisisobutyronitrile in ethyl acetate was placed in a screw capvial. The solution was sparged with nitrogen for 5 minutes, then thevial was sealed. The vial was placed in an oven at 65° C. for 7 hours.The solution was then precipitated into 60 mL of methanol. The resultantwhite solid was filtered and dried under vacuum. Analysis of the polymerby gel permeation chromatography in tetrahydrofuran showed M_(n)=2930and polydispersity=4.86. The polydispersity of the polymer is higherthan expected due to a multimodal distribution of molecular weights. Itis believed the multimodal distribution it is due to varying transferfrom each arm, or premature termination of the chains from each arm,yielding multiple arm lengths.

Example 8

[0142] Synthesis of a Poly(2-Ethylhexyl Acrylate) Star Polymer withAz-P(EHA)-TC and Trimethylolpropane.

[0143] A solution of 0.154 g (0.62 mmol) of the product of Example 1(AzTC), 4.30 g 2-ethylhexyl acrylate and 0.43 g of a 2 wt % solution of2,2′-azobisisobutyronitrile in ethyl acetate was placed in a screw capvial. The solution was sparged with nitrogen for 15 minutes, and thevial was sealed. The vial was heated in an oven at 70° C. for 3 hours. Asmall aliquot of the reaction mixture was weighed and was thenconcentrated to dryness by heating in an oven at 100° C. for 3 hours.The ratio of the mass of the dried sample to the mass of the aliquot ofreaction mixture was used to calculate the percent conversion of themonomer. The conversion was 94%. Analysis of the polymer by gelpermeation chromatography in tetrahydrofuran showed M_(n)=4825 andpolydispersity=2.15.

[0144] An aliquot of the above polymer solution (1.00 g) was mixed witha solution of 0.0032 g (0.024 mmol) trimethylolpropane in 0.3 g ethylacetate and 1 mg (0.007 mmol) 1,8-diazabicyclo[5.4.0]undec-7-ene. Thesolution was left to stand at room temperature for 48 hours. Analysis ofthe polymer solution by gel permeation chromatography in tetrahydrofuranshowed M_(n)=6759 and polydispersity=2.25.

Example 9

[0145] Synthesis of Az-Poly(IBA-block-EHA)-TC via the ControlledPolymerization of 2-Ethylhexyl Acrylate with Az-P(IBA)-TC.

[0146] A solution of 1.00 g (0.2 mmol) of the product of Example 6(Az-P(IBA)-TC; M_(n)=3630; polydispersity=1.83), 2.00 g 2-ethylhexylacrylate, 4.0 g ethyl acetate, and 0.15 g of a 2 wt % solution of2,2′-azobisisobutyronitrile in ethyl acetate was placed in a screw capvial. The solution was purged with nitrogen for 15 minutes, then thevial was sealed. The vial was placed in an oven at 70° C. for 4 hours.The solution was then precipitated into 150 mL of methanol. The liquidwas decanted from the polymer and an additional 150 mL of methanol wasadded. The mixture was shaken for 24 hours, then the solvent wasdecanted. The recovered polymer was dried under vacuum. Analysis of thepolymer by gel permeation chromatography in tetrahydrofuran showedM_(n)=9900 and polydispersity=2.88.

Example 10

[0147] Synthesis of Az-P(EHA)-TC via the Controlled Polymerization of2-Ethylhexyl Acrylate with AzTC using UV Irradiation.

[0148] Solutions of 2-ethylhexyl acrylate, Darocur 1173™ (Ciba SpecialtyChemical Corp., Tarrytown, N.Y.), and AzTC were mixed according to Table10.1 and placed in screw cap vials. The solutions were sparged withnitrogen for 15 minutes, sealed, and rolled under an UV lamp (SylvaniaF40/350BL) for 16 hours. Monomer conversion was 98% by gravimetricanalysis. Analysis of the polymers by gel permeation chromatography intetrahydrofuran is shown below. TABLE 10.1 Solution Composition andMolecular Weight Determination for Example 10. Darocur Sample EHA, g1173, g AzTC, g Mn, g/mol polydispersity 10-1 10.0 0.02 0.06 37,000 2.0410-2 10.0 0.02 0.10 22,500 2.07

We claim:
 1. A telechelic (co)polymer comprising polymerized units ofone or more free radically (co)polymerizable monomers, an firstazlactone terminal group; and a second terminal group selected from axanthate group, a thioxanthate group, or a dithioester group.
 2. Thecopolymer of claim 1 comprising two or more blocks of units obtainedfrom free radically (co)polymerizable monomers, wherein the blockcopolymer has first azlactone terminal group and a second terminal groupselected from a xanthate group, a thioxanthate group, or a dithioestergroup.
 3. The (co)polymer of claim 1 comprising polymerized unitsobtained from two or more radically (co)polymerizable monomers whereinthe copolymer has a composition that varies along the length of thepolymer chain from azlactone terminus to opposite terminus based on therelative reactivity ratios of the monomers and instantaneousconcentrations of the monomers during polymerization.
 4. The (co)polymerof claim 1, wherein said (co)polymer comprises polymerized monomer unitsselected from the group consisting of (meth)acrylic acid;(meth)acrylates; fumaric acid (and esters), itaconic acid (and esters),maleic anhydride; styrenics; vinyl halides; (meth)acrylonitrile;vinylidene halides; vinyl esters of carboxylic acids; amides of vinylamines; monomers containing a secondary, tertiary or quaternary aminogroup; butadienes; unsaturated alkylsulphonic acids or derivativesthereof; 2-vinyl-4,4-dimethylazlactone, and N-vinyl pyrrolidinone andmixtures thereof; said (co)polymer having a first azlactone terminalgroup and a second terminal group selected from a xanthate group, athioxanthate group, or a dithioester group.
 5. The (co)polymer of claim1 having the structure Az-(M¹)_(x)—S—Y, wherein S—Y is a xanthate groupof the formula R⁵—O—C(S)—S—, a thioxanthate group of the formulaR⁵—S—C(S)—S—, or a dithioester group of the formula R⁵—C(S)—S—, whereinR⁵ is selected from an alkyl group, a cycloalkyl group, an aryl group, aheterocyclic group or an arenyl group; M¹ is a monomer unit derived froma radically (co)polymerizable monomer unit having an average degree ofpolymerization x, and Az is an azlactone group of the formula:

wherein R¹ and R² are each independently selected from X, H, an alkylgroup, a cycloalkyl group, a heterocyclic group, an arenyl group and anaryl group, or R¹ and R² taken together with the carbon to which theyare attached form a carbocyclic ring; R³ and R⁴ are each independentlyselected from an alkyl group, a cycloalkyl group, an aryl group, anarenyl group, or R³ and R⁴ taken together with the carbon to which theyare attached form a carbocyclic ring; Q is a linking group selected froma covalent bond, (—CH₂—)_(o), —CO—O—(CH₂)_(o)—, —CO—O—(CH₂CH₂O)_(o)—,—CO—NR⁶—(CH₂)_(o)—, —CO—S—(CH₂)_(o)—, where o is 1 to 12, and R⁶ is H,an alkyl group, a cycloalkyl group, an arenyl group, a heterocyclicgroup or an aryl group; and n is 0 or
 1. 6. The (co)polymer of claim 5wherein at least one of R₁ and R₂ are methyl.
 7. The (co)polymer ofclaim 5 wherein at least one of R₃ and R₄ is a C₁ to C₄ alkyl group. 8.The (co)polymer of claim 1 having the structureAz-(M¹)_(x)(M²)_(x)-(M³)_(x) . . . (M^(Ω))_(x)—SY, wherein SY is axanthate group of the formula R⁵—O—C(S)—S—, a thioxanthate group of theformula R⁵—S—C(S)—S—, or a dithioester group of the formula R⁵—C(S)—S—,wherein R⁵ is selected from an alkyl group, a cycloalkyl group, an arylgroup, a heterocyclic group or an arenyl group; M¹ to M^(Ω) are eachpolymer blocks of monomer units derived from a radically(co)polymerizable monomer units having an average degree ofpolymerization x, each x is independent, and Az is an azlactone group ofthe formula:

wherein R¹ and R² are each independently selected from X, H, an alkylgroup, a cycloalkyl group, a heterocyclic group, an arenyl group and anaryl group, or R¹ and R² taken together with the carbon to which theyare attached form a carbocyclic ring; R³ and R⁴ are each independentlyselected from an alkyl group, a cycloalkyl group, an aryl group, anarenyl group, or R³ and R⁴ taken together with the carbon to which theyare attached form a carbocyclic ring; Q is a linking group selected froma covalent bond, (—CH₂—)_(o), —CO—O—(CH₂)_(o)—, —CO—O—(CH₂CH₂O)_(o)—,—CO—NR⁸—(CH₂)_(o)—, —CO—S—(CH₂)_(o)—, where o is 1 to 12, and R⁸ is H,an alkyl group, a cycloalkyl group, an arenyl group, a heterocyclicgroup or an aryl group; and n is 0 or
 1. 9. The (co)polymer of claim 8wherein at least one of R₁ and R₂ are methyl.
 10. The (co)polymer ofclaim 8 wherein at least one of R₃ and R₄ is a C₁ to C₄ alkyl group. 11.The (co) polymer of claim 1 having a star, comb, block, or hyperbranchedstructure.
 12. The (co) polymer of claim 1 having pendent, nucleophilicfunctional groups.
 13. The (co)polymer of claim 1 comprisinginterpolymerized monomer units having pendent, nucleophilic functionalgroups.
 14. The (co) polymer of claim 13 having pendent, nucleophilicfunctional groups.
 15. A polymer derived from the reaction between saidpendent, nucleophilic functional groups of claim 14 and said azlactoneterminal group.